JP6788574B2 - Semiconductor light emitting device - Google Patents

Description

The present invention relates to a semiconductor light emitting device.

Conventionally, the inventors of the present application have proposed the semiconductor light emitting device described in Patent Document 1. The semiconductor light emitting device described in Patent Document 1 includes an active layer, a pair of clad layers sandwiching the active layer, and a phase modulation layer optically coupled to the active layer, and the phase modulation layer includes a basic layer. The basic layer is provided with a plurality of different refractive index regions having different refractive indexes. When a square lattice is set in the phase modulation layer, the different refractive index region (main hole) is arranged so as to exactly coincide with the lattice points of the hole lattice. An auxiliary different refractive index region (secondary hole) is provided around the different refractive index region, and light having a predetermined beam pattern can be emitted.

International release WO2014 / 136962

However, in the case of a structure provided with a main hole and a sub hole, it is difficult to control the position accuracy between them with high control, and it is also difficult to improve the definition of the pattern such as shortening the lattice spacing. There is a problem that it is difficult to obtain.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a semiconductor light emitting device capable of obtaining a desired beam pattern more easily than before.

In order to solve the above-mentioned problems, the first semiconductor light emitting element is a semiconductor light emitting element including an active layer, a pair of clad layers sandwiching the active layer, and a phase modulation layer optically coupled to the active layer. In the element, the phase modulation layer includes a basic layer and a plurality of different refractive index regions having different refractive indexes from the basic layer, and has an XYZ Cartesian coordinate system in which the thickness direction of the phase modulation layer is the Z-axis direction. When a virtual square grid with a lattice constant a is set in the XY plane, the position of the center of gravity of each of the different refractive index regions is only a distance r from the grid point position in the virtual square grid. All of the different refractive index regions are arranged so as to be offset, and all the different refractive index regions have the same distance r in the XY plane, the distance r is 0 <r ≦ 0.3a, and the semiconductor light emission. The beam pattern (excluding spots) emitted from the element includes at least one: a straight line, a cross, a figure, a photograph, a CG (computer graphics), or a character, and is specific to the beam pattern in the XY plane. The complex amplitude F (X, Y) obtained by two-dimensional Fourier transform of the region has the intensity distribution I (X, Y) in the XY plane and the phase distribution P (X, Y) in the XY plane, with j as the imaginary unit. In use: given by F (X, Y) = I (X, Y) x exp {P (X, Y) j}, from each grid point of the virtual square grid in the phase modulation layer. Let φ be the angle formed by the direction toward the center of gravity of each of the corresponding different refractive index regions and the X-axis, let C be the constant, and let the x-th in the X-axis direction and the y-th virtual square lattice in the Y-axis direction be. the position of the point and (x, y), the position (x, y) angle phi (x, y) in the a, φ (x, y) = C × P (X, Y) meets the, respectively The shape of the different refractive index region in the XY plane is characterized by being a square, a regular hexagon, a regular octagon, or a regular hexagon.
The second semiconductor light emitting element is a semiconductor light emitting element including an active layer, a pair of clad layers sandwiching the active layer, and a phase modulation layer optically coupled to the active layer. An XYZ Cartesian coordinate system having a basic layer and a plurality of different refractive index regions having different refractive indexes from the basic layer and having the thickness direction of the phase modulation layer as the Z-axis direction is set, and in the XY plane, When a virtual square lattice with a lattice constant a is set, each of the different refractive index regions is arranged so that the position of the center of gravity thereof deviates from the lattice point position in the virtual square lattice by a distance r. , All the different refractive index regions have the same distance r in the XY plane, the distance r is 0 <r ≦ 0.3a, and the beam pattern emitted from the semiconductor light emitting element ( (Excluding spots) includes at least one: straight line, cross, figure, photograph, CG (computer graphics), or character, and is a complex obtained by two-dimensional Fourier transforming a specific region of the beam pattern in the XY plane. The amplitude F (X, Y) uses the intensity distribution I (X, Y) in the XY plane and the phase distribution P (X, Y) in the XY plane, with j as the imaginary unit: F (X, Y). ) = I (X, Y) × exp {P (X, Y) j}, and in the phase modulation layer, from each lattice point of the virtual square lattice, the corresponding different refractive index. The angle between the direction toward the center of gravity of the region and the X-axis is φ, the constant is C, and the positions of the x-th and y-th virtual square grid points in the X-axis direction are (x, y). ), And if the angle at the position (x, y) is φ (x, y), φ (x, y) = C × P (X, Y) is satisfied, and each of the different refractive index regions is within the XY plane. The shape of is characterized by being a rectangle, an ellipse, or a shape in which a part of two circles or ellipses overlap.
The third semiconductor light emitting element is a semiconductor light emitting element including an active layer, a pair of clad layers sandwiching the active layer, and a phase modulation layer optically coupled to the active layer. An XYZ Cartesian coordinate system having a basic layer and a plurality of different refractive index regions having different refractive indexes from the basic layer and having the thickness direction of the phase modulation layer as the Z-axis direction is set, and in the XY plane, When a virtual square grid with a lattice constant a is set, each of the different refractive index regions is arranged so that the position of the center of gravity thereof deviates from the grid point position in the virtual square grid by a distance r. , All the different refractive index regions have the same distance r in the XY plane, the distance r is 0 <r ≦ 0.3a, and the beam pattern emitted from the semiconductor light emitting element ( (Excluding spots) includes at least one: straight line, cross, figure, photograph, CG (computer graphics), or character, and is a complex obtained by two-dimensional Fourier transforming a specific region of the beam pattern in the XY plane. The amplitude F (X, Y) uses the intensity distribution I (X, Y) in the XY plane and the phase distribution P (X, Y) in the XY plane, with j as the imaginary unit: F (X, Y). ) = I (X, Y) × exp {P (X, Y) j}, and in the phase modulation layer, from each lattice point of the virtual square lattice, the corresponding different refractive index. The angle between the direction toward the center of gravity of the region and the X-axis is φ, the constant is C, and the positions of the x-th and y-th virtual square grid points in the X-axis direction are (x, y). ), And if the angle at the position (x, y) is φ (x, y), φ (x, y) = C × P (X, Y) is satisfied, and each of the different refractive index regions is within the XY plane. The shape of is trapezoidal, deformed so that the dimension in the minor axis near one end along the major axis of the ellipse is smaller than the dimension in the minor axis near the other end, or an ellipse. It is characterized in that one end along the long axis of is deformed into a sharp end protruding along the long axis direction.
The fourth semiconductor light emitting element is a semiconductor light emitting element including an active layer, a pair of clad layers sandwiching the active layer, and a phase modulation layer optically coupled to the active layer. An XYZ orthogonal coordinate system having a basic layer and a plurality of different refractive index regions having different refractive indexes from the basic layer and having the thickness direction of the phase modulation layer as the Z-axis direction is set, and in the XY plane, When a virtual square lattice having a lattice constant a is set, each of the different refractive index regions is arranged so that the position of the center of gravity thereof deviates from the position of the lattice point in the virtual square lattice by a distance r. All the different refractive index regions have the same distance r in the XY plane, the distance r is 0 <r ≦ 0.3a, and the beam pattern emitted from the semiconductor light emitting element ( (Excluding spots) includes at least one: straight line, cross, figure, photograph, CG (computer graphics), or character, and is a complex obtained by two-dimensional Fourier transforming a specific region of the beam pattern in the XY plane. The amplitude F (X, Y) uses the intensity distribution I (X, Y) in the XY plane and the phase distribution P (X, Y) in the XY plane, with j as the imaginary unit: F (X, Y). ) = I (X, Y) × exp {P (X, Y) j}, and in the phase modulation layer, from each lattice point of the virtual square lattice, the corresponding different refractive index. The angle formed by the direction toward the center of gravity of the region and the X-axis is φ, the constant is C, and the positions of the x-th and y-th virtual square grid points in the X-axis direction are (x, y). ), And if the angle at the position (x, y) is φ (x, y), φ (x, y) = C × P (X, Y) is satisfied, and the effective refractive index of the phase modulation layer is n. In this case, the wavelength λ ₀ (= 2 ^0.5 × a × n) selected by the phase modulation layer is included in the emission wavelength range of the active layer.
In the fifth semiconductor light emitting element, when the effective refractive index of the phase modulation layer is n in any of the first to third semiconductor light emitting elements, the wavelength λ ₀ (= a ×) selected by the phase modulation layer. n) is characterized in that it is included in the emission wavelength range of the active layer.
In the sixth semiconductor light emitting device, in any of the first to fifth semiconductor light emitting devices, in the phase modulation layer, all the different refractive index regions have the same figure and / or the same figure in the XY plane. It has the same area, and the plurality of different refractive index regions can be overlapped by a translation operation or a translation operation and a rotation operation.
In the seventh semiconductor light emitting device, in any one of the first , second , fourth , fifth, and sixth semiconductor light emitting devices, the shape of the different refractive index region in the XY plane has rotational symmetry. , Characterized by.
In the eighth semiconductor light emitting device, in any one of the first , second , fourth , fifth , sixth, and seventh semiconductor light emitting devices, the shape of the different refractive index region in the XY plane has mirror image symmetry. It is characterized by being.
In the ninth semiconductor light emitting device, in any of the first to eighth semiconductor light emitting devices, the phase modulation layer is formed with a substantially periodic structure of the different refractive index region for emitting a target beam pattern. It is characterized by including an inner region and an outer region including the different refractive index region that surrounds the inner region and whose center of gravity coincides with the grid point position of the square lattice.

In the case of this structure, the position of the center of gravity of the plane shape in the different refractive index region is deviated by the distance r within the above range, so that the position of the lattice point is adjusted to the direction of the vector toward the position of the center of gravity of the plane shape in the different refractive index region. , The phase difference of the beam changes. That is, the phase difference of the beam emitted from each different refractive index region can be controlled only by changing the position of the center of gravity, and the beam pattern formed as a whole can be made into a desired shape. At this time, the lattice points of the virtual square lattice may be outside the different refractive index region, or the lattice points of the virtual square lattice may be included inside the different refractive index region.

In such a semiconductor light emitting device, at least a single different refractive index region exists inside a circle having a radius of 0.62a from the lattice points of the virtual square lattice.

Further, in the semiconductor light emitting element of the embodiment, in the phase modulation layer, all the different refractive index regions are (a) the same figure, (b) the same area, and / or (c) in the XY plane. ) Have the same distance r, and (d) the plurality of different refractive index regions can be superposed by a translation operation or a translation operation and a rotation operation.

By providing any one or more of these conditions (a) to (d), it is possible to suppress the generation of noise light and 0th-order light that becomes noise in the beam pattern. Here, the 0th-order light is an optical output that is output in parallel in the Z direction, and is light that is not phase-modulated in the phase modulation layer. In the phase modulation layer of the present invention, if r = 0 is set as the distance r between the lattice point of the virtual square lattice and the different refractive index region, it functions as a photonic crystal laser of the square lattice that outputs parallel to the Z direction. Become. In the present invention, the case of r = 0 is not included. It can be considered that the present invention realizes the control of the beam pattern by applying perturbation to each hole position of the square lattice photonic crystal laser including the square lattice photonic crystal having a periodic structure. That is, the formation of the standing wave state in the direction parallel to the square lattice is based on the same principle as that of the square lattice photonic crystal, but by adding the diffraction designed based on the present invention to each pore position, A desired phase modulation can be applied to a plane wave diffracted in a direction perpendicular to the square lattice, and as a result, a desired beam pattern can be obtained. From the above viewpoint, the structure formed by the different refraction region included in the phase modulation layer of the present invention is referred to as a substantially periodic structure rather than a periodic structure.

Further, in the semiconductor light emitting device of the embodiment, the shape of each of the different refractive index regions in the XY plane is characterized by having rotational symmetry. In this semiconductor light emitting device, the shape of each of the different refractive index regions in the XY plane is preferably a rotationally symmetric shape such as a perfect circle, a square, a regular hexagon, a regular octagon, or a regular hexadecagon. Compared with the rotation asymmetric figure, these figures have less influence even if the pattern shifts in the rotation direction, so that the pattern can be patterned with high accuracy.

In the semi-conductor light emitting device of the embodiment, the shape in the XY plane of each of the modified refractive index areas is characterized in that it has mirror symmetry (line symmetry). In this semiconductor light emitting device, the shape of each of the different refractive index regions in the XY plane is preferably a rectangle, an ellipse, two circles, or a part of the ellipse overlapping. Compared with the rotation asymmetric figure, these figures can be patterned with high accuracy because the line segment position which is the reference of the line symmetry can be clearly known.

In the semiconductor light emitting device of the embodiment , the shape of the different refractive index region in the XY plane is not limited to the above-mentioned figure. For example, the shape of each of the different refractive index regions in the XY plane is such that the dimension in the minor axis direction near one end along the major axis of the trapezoidal or ellipse is the dimension in the minor axis direction near the other end. It is a shape deformed to be smaller than (oval shape), or a shape deformed from one end along the long axis of an ellipse to a sharp end protruding along the long axis direction (tear shape). It is characterized by that. Even in such a figure, the phase of the beam can be changed by shifting the position of the center of gravity of the plane shape in the different refractive index region by a distance r from the lattice point.

In the semiconductor light emitting element of the embodiment, when the effective refractive index of the phase modulation layer is n, the wavelength λ ₀ (= a × n) selected by the phase modulation layer is within the emission wavelength range of the active layer. It is characterized by being included. The phase modulation layer (diffraction grating layer) can select the wavelength λ ₀ of the emission wavelengths of the active layer and output it to the outside.

In the semiconductor light emitting element of the embodiment, when the effective refractive index of the phase modulation layer is n, the wavelength λ ₀ (= 2 ^0.5 × a × n) selected by the phase modulation layer is the active layer. It is characterized in that it is included in the emission wavelength range. The phase modulation layer (diffraction grating layer) can select the wavelength λ ₀ of the emission wavelengths of the active layer and output it to the outside.

In the semiconductor light emitting element of the embodiment, the beam pattern emitted from the semiconductor light emitting element includes at least one: spot, straight line, cross, lattice pattern, or character, and is a specific beam pattern in the XY plane. The complex amplitude distribution F (X, Y) obtained by two-dimensional Fourier transforming the region has the intensity distribution I (X, Y) in the XY plane and the phase distribution P (X, Y) in the XY plane, with j as the imaginary unit. Given by the following equation: F (X, Y) = I (X, Y) × exp {P (X, Y) j}, in the phase modulation layer, each lattice of the virtual square lattice Let φ be the angle formed by the X-axis and the direction toward the center of gravity of each of the corresponding different refractive index regions from the point, and let C be the constant. If the position of a square grid point is (x, y) and the angle at the position (x, y) is φ (x, y), then φ (x, y) = C × P (X, Y) is satisfied. It is characterized by.

The characters composed of the beam pattern have the meanings of characters from all over the world such as alphabet, Japanese, Chinese, and German, and in the case of Japanese, they include kanji, hiragana, and katakana. When trying to display such characters, the beam pattern is Fourier transformed to determine the position of the center of gravity of the different refractive index region in the direction of the angle φ corresponding to the phase part of the complex amplitude, which is a lattice of a virtual square lattice. You can shift it from the point position.

According to the semiconductor light emitting device of the present invention, a desired beam pattern can be easily obtained.

FIG. 1 is a diagram showing a configuration of a laser device. FIG. 2 is a diagram showing a configuration of a laser element. FIG. 3 is a chart showing the relationship between the material, the conductive type, and the thickness (nm) of each compound semiconductor layer constituting the laser element. FIG. 4 is a plan view of the phase modulation layer 6. FIG. 5 is a diagram for explaining the positional relationship of the different refractive index region. FIG. 6 is an example in which the refractive index substantially periodic structure of FIG. 4 is applied only within a specific region of the phase modulation layer. FIG. 7 is a diagram for explaining the relationship between the output beam pattern and the angle φ in the phase modulation layer 6. FIG. 8- (A) is a diagram for explaining the arrangement of the original pattern before the Fourier transform, and FIG. 8- (B) is a diagram for explaining the arrangement of the beam pattern obtained by the embodiment. FIG. 9 is a diagram showing the configuration of the laser element. FIG. 10- (A) is a diagram for explaining the original pattern used in the embodiment, and FIG. 10- (B) is an intensity distribution obtained by performing a two-dimensional Fourier transform on the original pattern used in the embodiment. 10- (C) is a diagram for explaining a phase distribution obtained by performing a two-dimensional Fourier transform on the original pattern used in the embodiment. FIG. 11- (A) is a diagram showing a part of the different refractive index distribution in the first embodiment, and FIG. 11- (B) is a diagram showing a beam pattern obtained in the first embodiment. is there. FIG. 12 is a graph showing the S / N ratio of the output beam pattern according to the relationship between the filling factor FF and the distance r (a). FIG. 13- (A) is an excerpt of a part of the different refractive index distribution in the second embodiment, and FIG. 13- (B) is a diagram showing the beam pattern obtained in the second embodiment. Is. FIG. 14 is a graph showing the S / N ratio of the output beam pattern according to the relationship between the filling factor FF and the distance r (a). 15- (A) is an excerpt of a part of the different refractive index distribution in the third embodiment, and FIG. 15- (B) shows the beam pattern obtained in the third embodiment. FIG. 16 is a graph showing the S / N ratio of the output beam pattern according to the relationship between the filling factor FF and the distance r (a). FIG. 17 is a graph showing the relationship between the distance r (a) and the S / N ratio in the case of FIG. FIG. 18 is a graph showing the relationship between the distance r (a) and the S / N ratio in the case of FIG. FIG. 19 is a graph showing the relationship between the distance r (a) and the S / N ratio in the case of FIG. FIG. 20 is a plan view showing the shape of each of the different refractive index regions 6B in the XY plane. FIG. 21 is a plan view showing the shape of each of the different refractive index regions 6B in the XY plane. FIG. 22- (A) is a diagram showing a wave vector at the time of Γ point oscillation in the phase modulation layer, and FIG. 22- (B) is a diagram showing a wave vector at the time of M point oscillation in the phase modulation layer. FIG. 23 is a diagram showing a target pattern. FIG. 24 is a diagram showing a phase distribution pattern of the phase modulation layer corresponding to FIG. 23. FIG. 25 is an electron micrograph of the hole shape of the phase modulation layer corresponding to FIG. 23. FIG. 26 is a photograph showing the beam pattern of the laser element corresponding to FIG. 23. FIG. 27 is a graph showing the relationship between the wavelength and the light intensity of the beam pattern of the laser element corresponding to FIG. 26. FIG. 28 is a graph showing the relationship between the peak current (mA) and the laser light peak intensity (mW) of the laser element corresponding to FIG. 26. FIG. 29 is a diagram showing an equal wavelength plot at the oscillation wavelength of the spectral spectrum / angle dependence measurement result of the light intensity of the laser element corresponding to FIG. 26. FIG. 30 is a graph showing the relationship between the wave number (2π / a) and the wavelength (nm) in the cross section along the Γ-X direction and the Γ-M direction in FIG. 29. FIG. 31 is a graph showing the measurement results regarding the relationship between the wave number (2π / a) and the wavelength (nm) in the cross section along the Γ-X direction and the Γ-M direction before oscillation in the element of FIG. 29. FIG. 32 is a diagram showing a target pattern. FIG. 33 is a diagram showing a phase distribution pattern of the phase modulation layer corresponding to FIG. 32. FIG. 34 is a diagram showing a beam pattern corresponding to FIG. 32. FIG. 35 is a graph showing the relationship between the wavelength and the light intensity of the beam pattern of the laser element corresponding to FIG. 32. FIG. 36 is a graph showing the relationship between the peak current (mA) and the light intensity (mW) of the laser element corresponding to FIG. 34. FIG. 37 is a diagram showing a target pattern. FIG. 38 is a diagram showing a phase distribution pattern of the phase modulation layer corresponding to FIG. 37. FIG. 39 is a diagram showing a beam pattern corresponding to FIG. 37. FIG. 40 is a graph showing the relationship between the wavelength and the light intensity of the beam pattern of the laser element corresponding to FIG. 37. FIG. 41 is a graph showing the relationship between the peak current (mA) and the light intensity (mW) of the laser element corresponding to FIG. 39. FIG. 42 is a diagram showing a target pattern. FIG. 43 is a diagram showing a phase distribution pattern of the phase modulation layer corresponding to FIG. 42. FIG. 44 is a diagram showing a beam pattern corresponding to FIG. 42. FIG. 45 is a graph showing the relationship between the wavelength and the light intensity of the beam pattern of the laser element corresponding to FIG. 42. FIG. 46 is a graph showing the relationship between the peak current (mA) and the light intensity (mW) of the laser element corresponding to FIG. 44. FIG. 47 is a diagram showing a target pattern. FIG. 48 is a diagram showing a phase distribution pattern of the phase modulation layer corresponding to FIG. 47. FIG. 49 is a diagram showing a beam pattern corresponding to FIG. 47. FIG. 50 is a graph showing the relationship between the wavelength and the light intensity of the beam pattern of the laser element corresponding to FIG. 47. FIG. 51 is a graph showing the relationship between the peak current (mA) and the light intensity (mW) of the laser element corresponding to FIG. 49.

Hereinafter, the laser element (semiconductor light emitting element) and the laser device according to the embodiment will be described. The same reference numerals are used for the same elements, and duplicate description will be omitted.

FIG. 1 is a diagram showing a configuration of a laser device.

A plurality of laser element LDs are arranged one-dimensionally or two-dimensionally on the support substrate SB. Each laser element LD is driven by a drive circuit DRV provided on the back surface or inside of the support substrate SB. That is, according to the instruction from the control circuit CONT, the drive circuit DRV supplies a drive current to each laser element LD. For example, a drive current is supplied to the laser elements LD arranged two-dimensionally in the order of the addresses in which they are arranged. A laser beam is emitted from the laser element LD from a direction perpendicular to the substrate in a direction having a specific inclination. When the laser element LDs are turned on in the order of the addresses, the object is scanned by the laser beam in a pseudo manner. The laser beam LB reflected by the object can be detected by a photodetector PD such as a photodiode.

A detection signal indicating the laser beam intensity detected by the photodetector PD is input to the control circuit CONT. When the laser element LD is pulse-driven, the photodetector PD can measure the time from the emission timing of the laser beam to the detection timing, that is, the distance to the object.

Such a laser device can be used, for example, in the following applications. For example, the three-dimensional shape of an object can be measured by irradiating the object with a laser beam and measuring the distance to the laser beam irradiation position. If the three-dimensional shape data is used, it can be used for various processing devices and medical devices. In addition, if a laser beam is output to a moving body such as a vehicle, the distance can be measured according to the direction to the obstacle, and it is used as a safety device that automatically controls or assists the brakes and handles according to the distance. It is also possible to do.

Hereinafter, the detailed structure of the semiconductor laser device used in the above-mentioned laser device will be described. The laser element can emit laser light having various intensity patterns.

FIG. 2 is a diagram showing a configuration of a laser element.

The laser element LD selects the laser light from the active layer 4 and outputs it to the outside. The structure of the laser element may be such that the laser light is incident into the phase modulation layer 6 from the main body of the laser element such as a semiconductor laser element via an optical fiber or directly as in the conventional case. .. The laser beam incident on the phase modulation layer 6 forms a predetermined mode in the phase modulation layer 6 according to the lattice of the phase modulation layer, and has a desired pattern in the direction perpendicular to the surface of the phase modulation layer 6. Is emitted to the outside.

The laser element LD is a laser light source that forms a standing wave in the XY in-plane direction and outputs a plane wave whose phase is controlled in the Z direction, and is an active layer 4 that generates laser light and an upper cladding that sandwiches the active layer 4. A layer 7 and a lower clad layer 2 and optical guide layers 3 and 5 provided between them and sandwiching the active layer 4 are provided, and a phase modulation layer 6 is provided between the upper clad layer 7 and the active layer 4. It is provided. In the structure shown in FIG. 2, the second electrode E2 is provided in the central region of the contact layer 8.

In this structure, the lower clad layer 2, the lower optical guide layer 3, the active layer 4, the upper optical guide layer 5, the phase modulation layer 6, the upper clad layer 7, and the contact layer 8 are sequentially laminated on the semiconductor substrate 1. The first electrode E1 is provided on the lower surface of the semiconductor substrate 1, and the second electrode E2 is provided on the upper surface of the contact layer 8. When a drive current is supplied between the first electrode E1 and the second electrode E2, electrons and holes are recombined in the active layer 4, and the active layer 4 emits light. The carriers contributing to these light emission and the generated light are efficiently trapped between the upper and lower optical guide layers 3 and 5 and the clad layers 2 and 7.

The laser light emitted from the active layer 4 enters the inside of the phase modulation layer 6 and forms a predetermined mode. The phase modulation layer 6 is composed of a basic layer 6A made of a first refractive index medium and a second refractive index medium having a refractive index different from that of the first refractive index medium, and a plurality of different refractive indexes existing in the basic layer 6A. It has a rate region 6B. The plurality of different refractive index regions 6B include a substantially periodic structure. The laser light incident on the phase modulation layer 6 is emitted to the outside as a laser beam perpendicular to the substrate surface via the upper clad layer 7, the contact layer 8, and the upper electrode E2.

When the effective refractive index of the phase modulation layer 6 is n, the wavelength λ ₀ (= a × n) selected by the phase modulation layer 6 is included in the emission wavelength range of the active layer 4. The phase modulation layer (diffraction grating layer) can select the wavelength λ ₀ of the emission wavelengths of the active layer and output it to the outside.

The oscillation state at this time corresponds to the Γ-point oscillation of the square lattice when the perturbation is 0, that is, when r = 0, as shown in FIG. 22- (A), and the oscillation state of the fundamental wave. As shown in the figure, the wave vector faces the horizontal direction (Γ-X direction) and the vertical direction (Γ-Y direction) in the plane of the phase modulation layer 6. The distance r is the distance between the lattice point position O of the virtual square lattice in the phase modulation layer 6 and the center of gravity of the hole, and r = 0 indicates the case where there is no perturbation. When r is not zero, a part of the standing waves generated in the plane is emitted to the outside perpendicularly to the substrate surface as a laser beam having a desired pattern. The reciprocal lattice vector is 2π / a times the basic vector.

Further, when the effective refractive index of the phase modulation layer 6 is n, the wavelength λ ₀ (= √2 × a × n) selected by the phase modulation layer 6 is included in the emission wavelength range of the active layer 4. .. Note that it is √2 ^{= 2 0.5.} The phase modulation layer (diffraction grating layer) can select the wavelength λ ₀ of the emission wavelengths of the active layer and output it to the outside. The oscillation state at this time corresponds to the M-point oscillation of the square lattice as shown in FIG. 22- (B) when the perturbation is 0, that is, when r = 0. As shown in FIG. 22- (B), the vector of the fundamental wave of the laser oscillation is rotated by 45 degrees as compared with the case of (A). More specifically, in the oscillation mode of (B), the oscillation wavelength remains the same as in the case of (A), but the oscillation direction in the lattice is different. In the oscillation mode of (A), a standing wave in which the main light wave travels in four directions along the grid of the square lattice is formed, but in the oscillation mode of (B), a direction rotated by 45 degrees, that is, a diagonal line is formed. The main light wave travels in the direction.

FIG. 3 is a chart showing the relationship between the material, the conductive type, and the thickness (nm) of each compound semiconductor layer constituting the laser element.

The material of each element is as shown in FIG. 3, the semiconductor substrate 1 is made of GaAs, the lower clad layer 2 is made of AlGaAs, the lower optical guide layer 3 is made of AlGaAs, and the active layer 4 is made of multiple quantum well structure MQW. (Barrier layer: AlGaAs / Well layer: InGaAs), the upper optical guide layer 5 is composed of the lower AlGaAs / upper GaAs, and the phase modulation layer (refractive index modulation layer) 6 has a basic layer 6A of GaAs and a basic layer 6A inside. The different refractive index region (embedded layer) 6B embedded in is made of AlGaAs, the upper clad layer 7 is made of AlGaAs, and the contact layer 8 is made of GaAs.

As shown in FIG. 3, each layer contains impurities of the first conductive type (N type) or impurities of the second conductive type (P type) (impurity concentration is 1 × 10 ¹⁷ to 1). × 10 ²¹ / cm ³ ), the region to which no impurities are intentionally added is true (type I). The concentration of type I impurities is 1 × 10 ¹⁵ / cm ³ or less.

Further, the energy bandgap of the clad layer is set to be larger than the energy bandgap of the optical guide layer, and the energy bandgap of the optical guide layer is set to be larger than the energy bandgap of the well layer of the active layer 4. In AlGaAs, the energy band gap and the refractive index can be easily changed by changing the composition ratio of Al. In Al _X Ga _1-X As, when the composition ratio X of Al having a relatively small atomic radius is decreased (increased), the energy band gap positively correlated with this becomes small (large), and the atomic radius becomes GaAs. When InGaAs is obtained by mixing a large amount of In, the energy band gap becomes small. That is, the Al composition ratio of the clad layer is larger than the Al composition ratio of the optical guide layer, and the Al composition ratio of the optical guide layer is higher than the Al composition of the barrier layer (AlGaAs) of the active layer. The Al composition ratio of the clad layer is set to 0.2 to 0.4, which is 0.3 in this example. The Al composition ratio of the barrier layer in the optical guide layer and the active layer is set to 0.1 to 0.15, which is 0.1 in this example.

The thickness of each layer is as shown in FIG. 3, the numerical range in the figure shows a preferable value, and the numerical value in parentheses shows an optimum value. Since the phase of the laser beam emitted from the phase modulation layer as a plane wave in the Z direction also depends on the characteristics of the phase modulation layer, it functions as a phase modulation layer.

As shown in FIG. 9, a phase modulation layer 6 may be provided between the lower clad layer 2 and the active layer 4. In this case, the phase modulation layer 6 can be arranged at a position sandwiched between the lower clad layer 2 and the optical guide layer 3. This structure also has the same effect as described above. That is, the laser light emitted from the active layer 4 is incident on the inside of the phase modulation layer 6 to form a predetermined mode. The laser beam incident in the phase modulation layer 6 passes through the lower light guide layer, the active layer 4, the upper light guide layer 5, the upper clad layer 7, the contact layer 8, and the upper electrode E2 as a laser beam on the substrate surface. It is emitted in the vertical direction. The laser beam can also be emitted at an angle perpendicular to the substrate surface.

Although not shown, the same effect can be obtained if the structure includes the phase modulation layer 6 and the active layer 4 between the upper clad layer 7 and the lower clad layer 2.

It is also possible to deform the electrode shape and emit laser light from the lower surface of the substrate. That is, when the first electrode E1 is open on the lower surface of the semiconductor substrate 1 in the region facing the second electrode E2, the laser beam is emitted from the lower surface to the outside. In this case, the first electrode E1 provided on the lower surface of the semiconductor substrate 1 is an opening electrode having an opening in the central portion, and an antireflection film may be provided in and around the opening of the first electrode E1. .. In this case, the antireflection film is composed of a dielectric single-layer film such as silicon nitride (SiN) or silicon dioxide (SiO ₂ ) or a dielectric multilayer film. Examples of the dielectric multilayer film include titanium oxide (TiO ₂ ), silicon dioxide (SiO ₂ ), silicon monoxide (SiO), niobium oxide (Nb ₂ O ₅ ), tantalum pentoxide (Ta ₂ O ₅ ), and foot. Dielectric layers such as magnesium oxide (MgF ₂ ), titanium oxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), cerium oxide (CeO ₂ ), indium oxide (In ₂ O ₃ ), zirconium oxide (ZrO ₂ ) A film in which two or more kinds of dielectric layers selected from the group are appropriately laminated can be used. For example, a film having a thickness of λ / 4 is laminated with an optical film thickness for light having a wavelength of λ. The reflective film and the antireflection film can be formed by using a sputtering method.

A second electrode E2 is provided on the upper surface of the contact layer 8, but a region other than the region where the contact electrode E2 is formed is covered with an insulating film such as SiO ₂ or silicon nitride, if necessary. , The surface can be protected.

In the above-mentioned structure, pores are periodically formed by etching at a plurality of locations of the basic layer 6A, and the different refractive index region 6B is formed in the formed pores by an organic metal vapor phase growth method, a sputtering method, or an epitaxial method. Although the method is embedded, even if the different refractive index region 6B is embedded in the pores of the basic layer 6A and then the different refractive index coating layer made of the same material as the different refractive index region 6B is deposited on it. Good.

FIG. 4 is a plan view of the above-mentioned phase modulation layer 6.

The phase modulation layer 6 includes a basic layer 6A made of a first refractive index medium and a different refractive index region 6B made of a second refractive index medium having a refractive index different from that of the first refractive index medium. The different refractive index region 6B is a compound semiconductor, but may be a pore filled with argon, nitrogen, air, or the like.

The plurality of different refractive index regions 6B includes only the first different refractive index regions 6B1 in the hole having the first area (area S1 in the XY plane) perpendicular to the thickness direction (Z axis), and the unit constituent regions R11 to R34. I have one in each. When the first different refractive index region 6B1 is circular, if its diameter is D, then S = π (D / 2) ² . The ratio of the area S of the first different refractive index region 6B1 to the one unit constituent region R11 to R34 is defined as the filling factor (FF). The area of one unit constituent area R11 to R34 is equal to the area of one virtual square lattice in one unit lattice.

Here, the unit constituent areas R11 to R34 are defined. Each unit constituent region R11 to R34 comprises only one first different refractive index region 6B1. The (center of gravity G) of the first different refractive index region 6B1 in the unit constituent regions R11 to R34 is located at a position shifted from the grid point O (see FIG. 5) of the virtual square lattice closest to the center of gravity G1.

With reference to FIG. 5, the angle formed by the direction from the grid point O of the virtual square grid toward the center of gravity G and the X axis is φ (x, y). x indicates the position of the x-th grid point on the X-axis, and y indicates the position of the y-th grid point on the Y-axis. When the rotation angle φ coincides with the positive direction of the X axis, φ = 0 °.

As shown in FIG. 4, in the phase modulation layer 6, a plurality of unit configuration regions R11 to R34 are two-dimensionally arranged in the XY plane including the X-axis and the Y-axis, and each unit configuration region Assuming that the XY coordinates are given at the position of the center of gravity of each unit constituent region, this position of the center of gravity coincides with the grid points of the virtual square lattice. Let the XY coordinates of the unit constituent areas R11 to R34 be (X, Y).

The coordinates of the unit constituent area R11 are (x1, y1), and the coordinates of the unit constituent region Rmn are (xm, yn) (m and n are natural numbers). At this time, the rotation angle distribution φ (x, y) is specified for each position determined by x (= x1, x2, x3, x4 ...) And y (= y1, y2, y3, y4 ...). It has a value, but it is not always represented by a specific function. That is, as described above, the rotation angle distribution φ (x, y) can be determined from the complex amplitude distribution obtained by Fourier transforming the output beam pattern of the present invention from which the phase distribution is extracted. This function can also be applied to the entire phase modulation layer or within a specific region.

FIG. 6 is an example in which the refractive index substantially periodic structure of FIG. 4 is applied only within a specific region of the phase modulation layer.

As shown in the plan view, a substantially periodic structure (eg, the structure of FIG. 4) for emitting a target beam pattern is formed inside the square inner region RIN. On the other hand, in the outer region ROUT surrounding the inner region RIN, a perfect circular different refractive index region having the same center of gravity position is arranged at the grid point position of the square lattice. For example, the filling factor FF in the outer region ROUT is set to 12%. Further, the lattice spacing of the square lattice virtually set is the same (= a) both inside the inner region RIN and in the outer region ROUT.

In the case of this structure, since the light is also distributed in the outer region ROUT, it is possible to suppress the generation of high frequency noise (so-called window function noise) generated by the sudden change in light intensity in the peripheral portion of the inner region RIN. There is an advantage that it can be done.

In the present invention, it is not necessary to use a polarizing plate, and the efficiency of light utilization is high.

FIG. 7 is a diagram for explaining the relationship between the output beam pattern and the angle φ in the phase modulation layer 6. This output beam pattern is a beam pattern observed by driving the present invention. The center of the figure corresponds to the direction perpendicular to the substrate of the present invention, and four quadrants with this as the origin are shown. In FIG. 7, an image is obtained in the first quadrant and the third quadrant as an example, but it is also possible to obtain an image in the second quadrant and the fourth quadrant or all quadrants. At this time, from the present invention, a beam pattern that is point-symmetrical with respect to the origin (that is, the direction perpendicular to the substrate of the device) can be obtained. Here, as an example, a case where the character "A" is rotated by 180 degrees in the third quadrant and the character "A" is rotated by 180 degrees in the first quadrant will be described. Of course, the beam pattern can also be obtained in a direction perpendicular to the substrate of the present invention, in which case a set of point-symmetrical patterns are observed overlapping at the same time, but a particularly rotationally symmetric beam pattern (for example, , Crosses, circles, double circles, etc.), they overlap and are observed as one pattern. Here, for the sake of simplicity, a case where images can be obtained in the first quadrant and the third quadrant will be described as an example.

In embodiments, the emitted beam pattern (excluding spots) includes at least one: a straight line, a cross, a graphic, a photograph, a CG (computer graphics), a grid pattern, or a letter. The characters composed of the beam pattern have the meanings of characters from all over the world such as alphabet, Japanese, Chinese, and German, and in the case of Japanese, they include kanji, hiragana, and katakana. For example, suppose you want to display the letter "A" in the first and third quadrants of an output beam pattern. In the first quadrant, the characters in the third quadrant are inverted. In this case, in order to design the phase modulation layer, the angle φ is obtained by the following procedure using the beam pattern of the third quadrant as the original image.

The complex amplitude distribution F (X, Y) obtained by two-dimensional Fourier transforming a specific region (in this case, the third quadrant) of the beam pattern in the XY plane has an intensity distribution I (X, Y) in the XY plane with j as an imaginary unit. It is expressed using Y) and the phase distribution P (X, Y) in the XY plane, and the intensity distribution and the phase distribution can be obtained.

That is, it is given by F (X, Y) = I (X, Y) × exp {P (X, Y) j}.

Here, in the phase modulation layer 6, the angle formed by the X-axis and the direction from each lattice point of the above-mentioned virtual square lattice toward the center of gravity G of the corresponding different refractive index regions is a constant. Is C, the position of the x-th virtual grid point in the X-axis direction and the y-th virtual square grid point in the Y-axis direction is (x, y), and the angle at the position (x, y) is φ (x, y). Then, the angle distribution φ (x, y) can be obtained by φ (x, y) = C × P (X, Y). Here, C is a constant and has the same value for all positions (x, y).

When the letter "A" is to be displayed, the beam pattern is Fourier transformed, and the position G of the center of gravity of the different refractive index region is set to the lattice of a virtual square lattice in the direction of the angle φ corresponding to the phase of the complex amplitude. It may be shifted from the point position O. By adjusting the angle φ, it is possible to obtain an arbitrary beam pattern or a pair of diagonal single peak beams. The far-field image after Fourier transform of the laser beam shall take various shapes such as a single or multiple spot shape, a ring shape, a linear shape, a character shape, a double ring shape, or a Laguerre Gaussian beam shape. Can be done.

Since the beam direction can also be controlled, it can be used in a laser processing machine or the like that electrically performs high-speed scanning by arranging the laser elements in one or two dimensions.

Further, as a method of obtaining the intensity distribution and the phase distribution from the complex amplitude distribution obtained by the Fourier transform, for example, for the intensity distribution I (x, y), by using the abs function of the numerical analysis software "MATLAB" of MathWorks. It can be calculated, and the phase distribution P (x, y) can be calculated by using the angular function of MATLAB.

The features of the beam pattern obtained by the present invention will be described. That is, as described above, the points to be noted when carrying out the present invention of determining the angle distribution from the Fourier transform result of the beam pattern and determining the arrangement of each hole will be described. When the beam pattern before the Fourier transform is divided into four quadrants 1, 2, 3 and 4 as shown in FIG. 8 (A), the beam pattern obtained from the present invention is as shown in FIG. 8 (B). That is, in the first quadrant of the beam pattern of the present invention, a pattern in which the first quadrant of FIG. 8 (A) is rotated 180 degrees and the third quadrant of FIG. 8 (A) are superimposed appears, and the beam of the present invention appears. In the second quadrant of the pattern, a pattern in which the second quadrant of FIG. 8 (A) is rotated 180 degrees and the fourth quadrant of FIG. 8 (A) are superimposed appears, and in the third quadrant of the beam pattern of the present invention. A pattern in which the third quadrant of FIG. 8 (A) is rotated 180 degrees and the first quadrant of FIG. 8 (A) are superimposed appears, and the fourth quadrant of the beam pattern of the present invention is the fourth quadrant of FIG. 8 (A). A pattern in which the four quadrants are rotated 180 degrees and the second quadrant in FIG. 8A is superimposed appears. Therefore, when a beam pattern (original pattern) before Fourier conversion that has a value only in the first quadrant is used, the first quadrant of the original pattern appears in the third quadrant in the beam pattern obtained from the present invention. In the beam pattern obtained from the present invention, only a pattern obtained by rotating the first quadrant of the original pattern by 180 degrees appears in the first quadrant.

Next, the amount of shifting the center of gravity position G of the different refractive index region from the lattice point position O of the virtual square lattice will be described. Assuming that the lattice constant that defines the interval of the center of gravity G is a, it is given by the filling factor FF = S / a ² in the different refractive index region. However, S is the area of the different refractive index region. For example, in the case of a perfect circle, if the diameter of the perfect circle is D, it is given by S = π × (D / 2) ² . Further, in the case of a square shape, if the length of one side of the square is L, it is given by S = L ² . The same applies to other shapes. Hereinafter, specific embodiments will be described. FIG. 10A is an image of an original pattern common to all embodiments unless otherwise specified. It is a character of "light" composed of 704 x 704 pixels. At this time, the character "light" exists in the first quadrant, and there is no pattern in the second to fourth quadrants. FIG. 10B is a two-dimensional Fourier transform of FIG. 10A to extract the intensity distribution, and is composed of 704 × 704 elements. FIG. 10C is a phase distribution extracted by performing a two-dimensional Fourier transform on FIG. 10A, and is composed of 704 × 704 elements. This also corresponds to the angle distribution, and FIG. 10C shows the distribution of angles from 0 to 2π depending on the shade of color. The black part represents the angle 0.

FIG. 11A is a partial excerpt of a top view of the different refractive index region in the first embodiment, and the different refractive index region in the basic layer is shown in white. Actually, there are 704 × 704 different refractive index regions. The planar shape of the different refractive index region is a perfect circle, the diameter of the hole D = 111 nm, the distance between the lattice point position O of the virtual square lattice and the center of gravity of the hole r = 8.52 nm, the lattice of the virtual square lattice. The constant a = 284 nm. At this time, the filling factor of a perfect circle is FF = 12%, and r = 0.03a. FIG. 11B is a predicted beam pattern obtained by Fourier transforming the entire different refractive index region.

FIG. 12 is a graph showing the S / N ratio of the output beam pattern, that is, the desired beam pattern and noise intensity ratio according to the relationship between the filling factor FF and the distance r (a) with respect to the first embodiment. is there. Further, FIG. 17 is a graph showing the relationship between the distance r (a) and the S / N ratio in the case of FIG.

In the case of this structure, when the distance r is at least 0.3a or less, the S / N is higher than when it exceeds 0.3a, and when the distance r is 0.01a or more, it is higher than when it is 0. It can be seen that the S / N is also high. In particular, looking at FIG. 17, there is a peak of the S / N ratio within these numerical ranges. That is, from the viewpoint of improving the S / N ratio, the distance r is preferably 0 <r ≦ 0.3a, more preferably 0.01a ≦ r ≦ 0.3a, and further preferably 0.03a ≦ r ≦ 0.25. preferable. However, even when r is smaller than 0.01a, a beam pattern can be obtained although the S / N ratio is small.

FIG. 13A is an excerpt of a top view of the different refractive index region in the second embodiment, and the different refractive index region in the basic layer is shown in white. Actually, there are 704 × 704 different refractive index regions. The planar shape of the different refractive index region is square, the length of one side is L = 98.4 nm, the distance between the lattice point position O of the virtual square lattice and the center of gravity of the hole is r = 8.52 nm, and the virtual square lattice. The lattice constant a = 284 nm. At this time, the filling factor of the square hole is FF = 12%, and r = 0.03a. FIG. 13B is a predicted beam pattern obtained by Fourier transforming the entire different refractive index region.

FIG. 14 is a graph showing the S / N ratio of the output beam pattern, that is, the desired beam pattern and noise intensity ratio according to the relationship between the filling factor FF and the distance r (a) with respect to the second embodiment. is there. Further, FIG. 18 is a graph showing the relationship between the distance r (a) and the S / N ratio in the case of FIG.

Even in the case of this structure, when the distance r is at least 0.3a or less, the S / N is higher than when it exceeds 0.3a, and when the distance r is 0.01a or more, it is 0. It can be seen that the S / N is higher than in the case. In particular, looking at FIG. 18, there is a peak of the S / N ratio within these numerical ranges. That is, from the viewpoint of improving the S / N ratio, the distance r is preferably 0 <r ≦ 0.3a, more preferably 0.01a ≦ r ≦ 0.3a, and further preferably 0.03a ≦ r ≦ 0.25a. preferable. However, even when r is smaller than 0.01a, a beam pattern can be obtained although the S / N ratio is small.

FIG. 15A is a partial excerpt of a top view of the different refractive index region in the third embodiment, and the different refractive index region in the basic layer is shown in white. Actually, there are 704 × 704 different refractive index regions. The planar shape of the different refractive index region is a shape in which two perfect circles overlap, and the diameters of the holes are both D = 111 nm, and the first hole has a center of gravity at the lattice point position O of the virtual square lattice. The second hole is arranged at a distance r = 14.20 nm between the center of gravity of the hole and the lattice point position O of the virtual square lattice. At this time, the lattice constant a = 284 nm of the virtual square lattice was set. At this time, the filling factor of a perfect circle is FF = 12%, and r = 0.05a. FIG. 13B is a predicted beam pattern obtained by Fourier transforming the entire different refractive index region.

FIG. 16 is a graph showing the S / N ratio of the output beam pattern, that is, the desired beam pattern and noise intensity ratio according to the relationship between the filling factor FF and the distance r (a). FIG. 19 is a graph showing the relationship between the distance r (a) and the S / N ratio in the case of FIG.

Even in the case of this structure, when the distance r is at least 0.3a or less, the S / N is higher than when it exceeds 0.3a, and when the distance r is 0.01a or more, it is 0. It can be seen that the S / N is higher than in the case. In particular, looking at FIG. 19, there is a peak of the S / N ratio within these numerical ranges. That is, from the viewpoint of improving the S / N ratio, the distance r is preferably 0 <r ≦ 0.3a, more preferably 0.01a ≦ r ≦ 0.3a, and even more preferably 0.03a ≦ r0.25a. However, even when r is smaller than 0.01a, a beam pattern can be obtained although the S / N ratio is small.

Further, in the cases of FIGS. 12, 14, and 16, the regions where the S / N ratio exceeds 0.9, 0.6, and 0.3 are given by the following functions. In FIGS. 17, 18, and 19, FF3, FF6, FF9, FF12, FF15, FF18, FF21, FF24, FF27, and FF30 are FF = 3%, FF = 6%, and FF = 9%, respectively. It shows FF = 12%, FF = 15%, FF = 18%, FF = 21%, FF = 24%, FF = 27%, FF = 30%.
(S / N is 0.9 or more in FIG. 12)
FF> 0.03 and
r> 0.06 and
r <-FF + 0.23 and r> -FF + 0.13
(S / N is 0.6 or more in FIG. 12)
FF> 0.03 and
r> 0.03 and
r <-FF + 0.25 and
r> -FF + 0.12
(S / N is 0.3 or more in FIG. 12)
FF> 0.03 and
r> 0.02 and
r <-(2/3) FF + 0.30 and r>-(2/3) FF + 0.083
(S / N is 0.9 or more in FIG. 14)
r> -2FF + 0.25 and
r <-FF + 0.25 and
r> FF-0.05
(S / N is 0.6 or more in FIG. 14)
FF> 0.03 and
r> 0.04 and
r <-(3/4) FF + 0.2375, and
r> -FF + 0.15
(S / N is 0.3 or more in FIG. 14)
FF> 0.03 and
r> 0.01 and
r <-(2/3) FF + 1/3 and r>-(2/3) FF + 0.10
(S / N is 0.9 or more in FIG. 16)
r> 0.025 and
r>-(4/3) FF + 0.20 and r <-(20/27) FF + 0.20
(S / N is 0.6 or more in FIG. 16)
FF> 0.03 and
r> 0.02 and
r>-(5/4) FF + 0.1625, and
r <-(13/18) FF + 0.222
(S / N is 0.3 or more in FIG. 16)
FF> 0.03 and
r> 0.01 and
r <-(2/3) FF + 0.30 and
r>-(10/7) FF + 1/7

In the above-mentioned structure, if the structure includes the active layer 4 and the phase modulation layer 6, the material system, the film thickness, and the layer structure have a degree of freedom. Here, the scaling law holds for the so-called square lattice photonic crystal laser when the perturbation from the virtual square lattice is 0. That is, when the wavelength becomes a constant α times, the same standing wave state can be obtained by multiplying the entire cubic lattice structure by α. Similarly, in the present invention, it is possible to determine the structure of the phase modulation layer by the scaling law at wavelengths other than those disclosed in the examples. Therefore, it is also possible to realize a semiconductor light emitting device that outputs visible light by using an active layer that emits light such as blue, green, and red and applying a scaling law according to a wavelength. In the manufacture of laser devices, each compound semiconductor layer uses an organometallic vapor phase growth (MOCVD) method. Crystal growth is performed on the (001) plane of the semiconductor substrate 1, but the crystal growth is not limited to this. Further, in the production of the laser element using the above-mentioned AlGaN, the growth temperature of AlGaAs is 500 ° C. to 850 ° C., and 550 to 700 ° C. is adopted in the experiment, and TMA (trimethylaluminum) is used as the Al raw material during growth. ), TMG (trimethyl gallium) and TEG (triethyl gallium as a gallium raw material), AsH ₃ as the as raw material (arsine), Si ₂ H ₆ as a raw material for N-type impurity (disilane), DEZn as a raw material for P-type impurity (Diethylzinc) is used. In the growth of GaAs, TMG and arsine are used, but TMA is not used. InGaAs is manufactured using TMG, TMI (trimethylindium) and arsine. The insulating film may be formed by sputtering a target using the constituent substance as a raw material.

That is, the above-mentioned laser element first has an N-type clad layer (AlGaAs) 2, a guide layer (AlGaAs) 3, and a multiple quantum well structure (InGaAs / AlGaAs) 4 on an N-type semiconductor substrate (GaAs) 1. The optical guide layer (GaAs / AaGaAs) 5 and the basic layer (GaAs) 6A to be the phase modulation layer are sequentially epitaxially grown by using the MOCVD (metalorganic vapor phase growth) method. Next, in order to perform alignment after epitaxial growth, a SiN layer is formed on the basic layer 6A by a PCVD (plasma CVD) method, and then a resist is formed on the SiN layer. Further, the resist is exposed and developed, the SiN layer is etched using the resist as a mask, and a part of the SiN layer remains to form an alignment mark. Remove the remaining resist.

Next, another resist is applied to the basic layer 6A, a two-dimensional fine pattern is drawn on the resist with an electron beam drawing device based on the alignment mark, and the two-dimensional fine pattern is formed on the resist by developing the resist. .. Then, using the resist as a mask, a two-dimensional fine pattern having a depth of about 100 nm is transferred onto the basic layer 6A by dry etching to remove the resist that forms holes. The depth of the pores is 100 nm. In the pores, the compound semiconductor to be the different refractive index region 6B (AlGaAs) is re-grown to the depth of the pores or more. Next, the upper clad layer (AlGaAs) 7 and the contact layer (GaAs) 8 are sequentially formed by MOCVD, and an appropriate electrode material is formed on the upper and lower surfaces of the substrate by a vapor deposition method or a sputtering method to form the first and second electrodes. Form. Further, if necessary, an insulating film can be formed on the upper and lower surfaces of the substrate by a sputtering method or the like.

When the phase modulation layer is provided below the active layer, the phase modulation layer may be formed on the lower clad layer before the active layer and the lower optical guide layer are formed.

When manufacturing a laser element main body without a phase modulation layer, this manufacturing step may be omitted. Further, a columnar different refractive index region may be used as a void, and a gas such as air, nitrogen or argon may be enclosed. The spacing between the vertical and horizontal grid lines in the above-mentioned virtual square grid is about the wavelength divided by the equivalent refractive index or the wavelength divided by the equivalent refractive index and √2, specifically 300 nm. It is preferably set to about 210 nm. In the case of a square lattice with a lattice spacing a, if the unit vectors of Cartesian coordinates are x and y, the basic translation vectors a ₁ = ax and a ₂ = ay, and the basic reciprocal lattice vectors with respect to the translation vectors a ₁ and a _2. b ₁ = (2π / a) y, b ₂ = (2π / a) x. When the wave vector of the wave existing in the lattice is k = nb ₁ + mb ₂ (n and m are arbitrary integers), the wave number k exists at the Γ point, but the magnitude of the wave vector is basically the reverse. When it is equal to the magnitude of the lattice vector, a resonance mode (standing wave in the XY plane) in which the lattice spacing a is equal to the wavelength λ is obtained. In the present invention, oscillation in such a resonance mode (standing wave state) can be obtained. At this time, considering the TE mode in which the electric field exists in the plane parallel to the square lattice, there are four modes in the standing wave state in which the lattice spacing and the wavelength are equal in this way due to the symmetry of the square lattice. In the present invention, a desired beam pattern can be similarly obtained when oscillating in any of the four standing wave modes.

The standing wave in the phase modulation layer described above is scattered by the hole shape, and the wave surface obtained in the direction perpendicular to the plane is phase-modulated to obtain a desired beam pattern. Therefore, a desired beam pattern can be obtained without a polarizing plate. This beam pattern is not only a pair of single-peak beams (spots), but as described above, a character shape, two or more spots having the same shape, or a vector whose phase and intensity distribution are spatially non-uniform. It can also be a beam or the like.

The refractive index of the basic layer 6A is preferably 3.0 to 3.5, and the refractive index of the different refractive index region 6B is preferably 1.0 to 3.4. The average diameter of each different refractive index region 6B1 in the pores of the basic layer 6A is, for example, 38 nm to 76 nm. By changing the size of this hole, the diffraction intensity in the Z-axis direction changes. This diffraction efficiency is proportional to the optical coupling coefficient κ1 represented by the first-order coefficient when the pore shape is Fourier transformed. The photocoupling coefficient is described, for example, in K. Sakai et al., "Coupled-Wave Theory for Square-Lattice Photonic Crystal Lasers With TE Polarization, IEEE J.Q. E. 46, 788-795 (2010)".

As described above, the above-mentioned semiconductor light emitting element is a semiconductor light emitting element including an active layer, a pair of clad layers sandwiching the active layer, and a phase modulation layer optically coupled to the active layer. The modulation layer includes a basic layer and a plurality of different refractive index regions having different refractive indexes from the basic layer, and sets an XYZ Cartesian coordinate system in which the thickness direction of the phase modulation layer is the Z-axis direction, and in the XY plane. When a square lattice with a virtual lattice constant a is set, each Cartesian index region is arranged so that the position of its center of gravity deviates from the position of the lattice point in the virtual square lattice by a distance r. The distance r is characterized in that 0 <r ≦ 0.3a.

In the case of this structure, the position of the center of gravity of the different refractive index region is deviated by the distance r within the above range, so that the position of the beam depends on the direction of the vector from the position of the lattice point toward the position of the center of gravity of the different refractive index region. The phase difference changes. That is, the phase difference of the beam emitted from each different refractive index region can be controlled only by changing the position of the center of gravity, and the beam pattern formed as a whole can be made into a desired shape. In such a semiconductor light emitting device, at least a single different refractive index region exists inside a circle having a radius of 0.62a from the lattice points of the virtual square lattice.

Further, in the phase modulation layer, all the different refractive index regions 6B have (a) the same figure, (b) the same area, and / or (c) the same distance r in the XY plane. (D) The plurality of different refractive index regions can be superposed by a translation operation or a translation operation and a rotation operation.

By providing any one or more of these conditions (a) to (d), it is possible to suppress the generation of noise and 0th-order light that becomes noise in the beam pattern.

20 and 21 are plan views showing the shapes of the respective different refractive index regions 6B in the XY plane.

In the case of FIG. 20A, the shape of the different refractive index region 6B in the XY plane has rotational symmetry. That is, the shape of each different refractive index region in the XY plane is a perfect circle, a square, a regular hexagon, a regular octagon, or a regular hexadecagon. Compared with the rotation asymmetric figure, these figures have less influence even if the pattern shifts in the rotation direction, so that the pattern can be patterned with high accuracy.

In the case of FIG. 20B, the shape of each different refractive index region in the XY plane has mirror image symmetry (line symmetry). That is, the shape of each different refractive index region in the XY plane is a shape in which a rectangle, an ellipse, two circles, or a part of the ellipse overlap. The lattice points O of the virtual square lattice exist outside these different refractive index regions.

Compared with the rotation asymmetric figure, these figures can be patterned with high accuracy because the line segment position which is the reference of the line symmetry can be clearly known.

In the case of FIG. 20C, the shape of each different refractive index region in the XY plane is such that the dimension in the minor axis direction near one end along the long axis of the trapezoid or ellipse is near the other end. A shape deformed to be smaller than the dimension in the minor axis direction (oval shape), or a shape deformed from one end along the long axis of the ellipse to a pointed end protruding along the long axis direction (oval shape) Tear type). The lattice points O of the virtual square lattice exist outside these different refractive index regions. Even in such a figure, the phase of the beam can be changed by shifting the position of the center of gravity of the different refractive index region by a distance r from the lattice point O of the virtual square lattice.

In the case of FIG. 21 (D), the shape of each different refractive index region in the XY plane has mirror image symmetry (line symmetry). That is, the shape of each different refractive index region in the XY plane is a shape in which a rectangle, an ellipse, two circles, or a part of the ellipse overlap. The lattice points O of the virtual square lattice exist inside these different refractive index regions.

Compared with the rotation asymmetric figure, these figures can be patterned with high accuracy because the line segment position which is the reference of the line symmetry can be clearly known. Further, since the distance r between the lattice point O of the virtual square lattice and the position of the center of gravity of the different refractive index region is small, it is possible to reduce the occurrence of noise in the beam pattern.

In the case of FIG. 21 (E), the shape of each different refractive index region in the XY plane is such that the dimension in the minor axis direction near one end along the long axis of the trapezoid or ellipse is near the other end. A shape deformed to be smaller than the dimension in the minor axis direction (oval shape), or a shape deformed from one end along the long axis of the ellipse to a pointed end protruding along the long axis direction (oval shape) Tear type). The lattice points O of the virtual square lattice exist inside these different refractive index regions. Even in such a figure, the phase of the beam can be changed by shifting the position of the center of gravity of the different refractive index region by a distance r from the lattice point O of the virtual square lattice. Further, since the distance r between the lattice point O of the virtual square lattice and the position of the center of gravity of the different refractive index region is small, the generation of noise in the beam pattern can be reduced.

FIG. 23 is an image of the target pattern, showing the characters “iPM Lasers”. At this time, the characters "iPM Lasers" exist in the first quadrant, and there are no patterns in the second to fourth quadrants.

FIG. 24 is a diagram showing a phase distribution pattern obtained by extracting a phase distribution by performing a two-dimensional Fourier transform on the image of FIG. 23. FIG. 24 shows the phase distribution of 0 to 2π depending on the shade of color. The black part represents phase 0. In the present invention, the rotation angle Φ of the hole as shown in FIG. 5 is determined according to this phase.

FIG. 25 is an electron micrograph showing the pore shape of the phase modulation layer for obtaining the image of FIG. 23. 1400 × 1400 holes are arranged on the grid points of the square grid in the phase modulation layer, and the grid point positions and the center of gravity of the pores are arranged with respect to the virtually set grid spacing (= a) of the square grid. The distance r = 0.06a and the filling factor FF = 20%. FIG. 25 shows some, but not all, 1400 × 1400 holes.

FIG. 26 is a photograph showing the beam pattern of the laser element corresponding to FIG. 23.

In this example, the size of the second electrode E2 on the p side of the laser element is 400 μm × 400 μm, and a pulse current of 10 kHz, 50 ns, and 4 A is supplied to the laser element LD of FIG. 2 to drive the laser element. The letters "iPM Lasers" and the letters rotated 180 ° appear in the first and third quadrants.

FIG. 27 is a graph showing the relationship between the wavelength and the light intensity of the beam pattern of the laser element corresponding to FIG. 26.

The intensity peak of the laser beam appears at a position exceeding the wavelength of 930 nm.

FIG. 28 is a graph showing the relationship between the peak current (mA) and the laser light peak intensity (mW) of the laser element corresponding to FIG. 26.

The data indicated by "whole" in the figure is an example in which the power meter light receiving unit is installed so as to include the entire output light of the laser light, and the laser light is measured. The data indicated by "0th-order light" in the figure is an example in which a power meter light receiving unit is installed so as to include only the 0th-order light located at the center of the laser light, and the laser light is measured. The data indicated by "each modulated light (estimated)" in the figure is a value calculated from "the above (" overall "-" 0th order light ") / 2" and indicates the estimated light intensity of the modulated light.

From the figure, it can be seen that the peak intensity of the laser beam increases as the peak current increases. Further, from the point where the peak current exceeds 1200 mA, it can be seen that the overall peak intensity increases linearly and with a large slope.

FIG. 29 is a diagram showing an equal wavelength plot at the oscillation wavelength (930.2 nm) of the spectral spectrum / angle dependence measurement result of the light intensity of the laser element corresponding to FIG. 26.

The letters "iPM Lasers" and their inverted letters appear in the first and third quadrants. From this result, it can be seen that the light having a single wavelength corresponding to the oscillation wavelength is emitted in the direction corresponding to the beam pattern shown in FIG. That is, it can be seen that the beam pattern is not composed of a combination of light of various wavelengths, and a beam pattern having a complicated shape can be realized even with a single wavelength.

FIG. 30 is a graph showing the relationship between the wave number (2π / a) and the wavelength (nm) in the cross section along the Γ-X direction and the Γ-M direction during oscillation (that is, during oscillation (applied current 4A)). That is, it is a figure which showed which wavelength light is emitted in which direction at the time of laser oscillation. The light of 930.2 nm plotted in FIG. 29 is emitted in the directions corresponding to the letters “L”, “a”, and “M” in FIG. 29, respectively. Light is also emitted above the Γ point.

FIG. 31 is a graph showing the relationship between the wave number (2π / a) and the wavelength (nm) in the cross section along the same direction as in FIG. 30 before oscillation (applied current 400 mA). That is, it is a figure which showed which wavelength light is emitted in which direction before laser oscillation. For a periodic structure such as a square lattice, it is a so-called photonic band structure. In the photonic band structure, a portion having a zero slope is called a band end, and it is known that a standing wave is formed at the band end. It is basically the band end that forms the oscillation mode due to the light confinement effect of the periodic structure. In FIG. 31, the slope of each band is zero on the Γ point (the portion where the wave number on the horizontal axis is 0), and an oscillation mode may be formed. On the other hand, there is no band end other than the Γ point, and there is no possibility that an oscillation mode will be formed. Of the points where the emitted light was observed in FIG. 30, there are no bands or band ends other than the Γ point. From this, the oscillation occurs at the Γ point, and part of the light oscillated at the Γ point is combined and emitted in the direction corresponding to the letters “L”, “a”, and “M”. I understand.

FIG. 32 is an image of the target pattern, showing a photograph of a person. At this time, the photograph of the person exists in the first quadrant, and there is no pattern in the second to fourth quadrants.

FIG. 33 is a diagram showing a phase distribution pattern obtained by extracting a phase distribution by performing a two-dimensional Fourier transform on the image of FIG. 32. FIG. 33 shows the phase distribution of 0 to 2π depending on the shade of color. The black part represents phase 0. In the present invention, the rotation angle Φ of the hole as shown in FIG. 5 is determined according to this phase.

In the phase modulation layer, holes of 1400 × 1400 are arranged substantially on the grid points of the square grid, and the grid point positions are relative to the virtually set grid spacing (= a) of the square grid. The distance between the hole and the center of gravity of the hole is r = 0.06a, and the filling factor FF = 20%.

FIG. 34 is a photograph showing the beam pattern of the laser element corresponding to FIG. 32.

In this example, the size of the second electrode E2 on the p side of the laser element is 400 μm × 400 μm, and a pulse current of 10 kHz, 50 ns, and 4 A is supplied to the laser element LD of FIG. 2 to drive the laser element. An image of a person and an image rotated by 180 ° appear in the first and third quadrants, respectively.

FIG. 35 is a graph showing the relationship between the wavelength and the light intensity of the beam pattern of the laser element corresponding to FIG. 32.

The intensity peak of the laser beam appears at a position exceeding the wavelength of 930 nm.

FIG. 36 is a graph showing the relationship between the peak current (mA) and the laser light peak intensity (mW) of the laser element corresponding to FIG. 34.

The data indicated by "whole" in the figure is an example in which the power meter light receiving unit is installed so as to include the entire output light of the laser light, and the laser light is measured. The data indicated by "0th-order light" in the figure is an example in which a power meter light receiving unit is installed so as to include only the 0th-order light located at the center of the laser light, and the laser light is measured. The data indicated by "each modulated light (estimated)" in the figure is a value calculated from "the above (" overall "-" 0th order light ") / 2" and indicates the estimated light intensity of the modulated light.

From the figure, it can be seen that the peak intensity of the laser beam increases as the peak current increases. Further, from the point where the peak current exceeds 1000 mA, it can be seen that the overall peak intensity increases linearly and with a large slope.

FIG. 37 is an image of the target pattern, showing a photograph of a person. At this time, the photograph of the person exists in the first quadrant, and there is no pattern in the second to fourth quadrants.

FIG. 38 is a diagram showing a phase distribution pattern obtained by extracting a phase distribution by performing a two-dimensional Fourier transform on the image of FIG. 37. FIG. 38 shows the phase distribution of 0 to 2π depending on the shade of color. The black part represents phase 0. In the present invention, the rotation angle Φ of the hole as shown in FIG. 5 is determined according to this phase.

In the phase modulation layer, holes of 1400 × 1400 are arranged substantially on the grid points of the square grid, and the grid point positions are relative to the virtually set grid spacing (= a) of the square grid. The distance between the hole and the center of gravity of the hole is r = 0.06a, and the filling factor FF = 20%.

FIG. 39 is a photograph showing the beam pattern of the laser element corresponding to FIG. 37.

In this example, the size of the second electrode E2 on the p side of the laser element is 400 μm × 400 μm, and a pulse current of 10 kHz, 50 ns, and 4 A is supplied to the laser element LD of FIG. 2 to drive the laser element. An image of a person and an inverted image of it appear in the first and third quadrants, respectively.

FIG. 40 is a graph showing the relationship between the wavelength and the light intensity of the beam pattern of the laser element corresponding to FIG. 37.

The intensity peak of the laser beam appears at a position exceeding the wavelength of 930 nm.

FIG. 41 is a graph showing the relationship between the peak current (mA) and the laser light peak intensity (mW) of the laser element corresponding to FIG. 39.

The data indicated by "whole" in the figure is an example in which the power meter light receiving unit is installed so as to include the entire output light of the laser light, and the laser light is measured. The data indicated by "0th-order light" in the figure is an example in which a power meter light receiving unit is installed so as to include only the 0th-order light located at the center of the laser light, and the laser light is measured. The data indicated by "each modulated light (estimated)" in the figure is a value calculated from "the above (" overall "-" 0th order light ") / 2" and indicates the estimated light intensity of the modulated light.

From the figure, it can be seen that the peak intensity of the laser beam increases as the peak current increases. Further, from the point where the peak current exceeds 1000 mA, it can be seen that the overall peak intensity increases linearly and with a large slope.

FIG. 42 is an image of the target pattern, showing the grid pattern. At this time, the grid pattern exists in the center. The grid pattern includes a straight line, which is a graphic and can be a photograph, or may be created by CG (computer graphics).

FIG. 43 is a diagram showing a phase distribution pattern obtained by extracting a phase distribution by performing a two-dimensional Fourier transform on the image of FIG. 42. FIG. 43 shows the phase distribution of 0 to 2π depending on the shade of color. The black part represents phase 0. In the present invention, the rotation angle Φ of the hole as shown in FIG. 5 is determined according to this phase.

In the phase modulation layer, holes of 1400 × 1400 are arranged substantially on the grid points of the square grid, and the grid point positions are relative to the virtually set grid spacing (= a) of the square grid. The distance between the hole and the center of gravity of the hole is r = 0.10a, and the filling factor FF = 20%.

FIG. 44 is a photograph showing the beam pattern of the laser element corresponding to FIG. 42.

In this example, the size of the second electrode E2 on the p side of the laser element is 400 μm × 400 μm, and a pulse current of 10 kHz, 50 ns, and 4 A is supplied to the laser element LD of FIG. 2 to drive the laser element. A grid pattern appears in the center.

FIG. 45 is a graph showing the relationship between the wavelength and the light intensity of the beam pattern of the laser element corresponding to FIG. 42.

The intensity peak of the laser beam appears at a position exceeding the wavelength of 930 nm.

FIG. 46 is a graph showing the relationship between the peak current (mA) and the laser light peak intensity (mW) of the laser element corresponding to FIG. 44.

The data indicated by "whole" in the figure is an example in which the power meter light receiving unit is installed so as to include the entire output light of the laser light, and the laser light is measured.

From the figure, it can be seen that the peak intensity of the laser beam increases as the peak current increases. Further, from the point where the peak current exceeds 3000 mA, it can be seen that the overall peak intensity increases with a large slope.

FIG. 47 is an image of the target pattern, and shows a multi-point pattern composed of a plurality of spots (dots) arranged at grid point positions of a virtual square grid. A total of 25 dots are shown, 5 in the vertical direction and 5 in the horizontal direction. At this time, the multipoint pattern exists in the center.

FIG. 48 is a diagram showing a phase distribution pattern obtained by extracting a phase distribution by performing a two-dimensional Fourier transform on the image of FIG. 47. FIG. 48 shows the phase distribution of 0 to 2π depending on the shade of color. The black part represents phase 0. In the present invention, the rotation angle Φ of the hole as shown in FIG. 5 is determined according to this phase.

In the phase modulation layer, holes of 1400 × 1400 are arranged substantially on the grid points of the square grid, and the grid point positions are relative to the virtually set grid spacing (= a) of the square grid. The distance between the hole and the center of gravity of the hole is r = 0.10a, and the filling factor FF = 20%.

FIG. 49 is a photograph showing the beam pattern of the laser element corresponding to FIG. 47.

In this example, the size of the second electrode E2 on the p side of the laser element is 400 μm × 400 μm, and a pulse current of 10 kHz, 50 ns, and 4 A is supplied to the laser element LD of FIG. 2 to drive the laser element. A multi-point pattern appears in the center.

FIG. 50 is a graph showing the relationship between the wavelength and the light intensity of the beam pattern of the laser element corresponding to FIG. 47.

The intensity peak of the laser beam appears at a position exceeding the wavelength of 930 nm.

FIG. 51 is a graph showing the relationship between the peak current (mA) and the laser light peak intensity (mW) of the laser element corresponding to FIG. 49.

The data indicated by "whole" in the figure is an example in which the power meter light receiving unit is installed so as to include the entire output light of the laser light, and the laser light is measured.

From the figure, it can be seen that the peak intensity of the laser beam increases as the peak current increases. Further, from the point where the peak current exceeds 3000 mA, it can be seen that the overall peak intensity increases with a large slope.

As described above, the beam pattern emitted from the semiconductor light emitting device can include at least one: spot, straight line, cross, grid pattern, figure, photograph, CG (computer graphics), or character. ..

6 ... Phase modulation layer, 6A ... Basic layer, 6B ... Different refractive index region.

Claims (9)

With the active layer
A pair of clad layers sandwiching the active layer and
A phase modulation layer optically coupled to the active layer and
In a semiconductor light emitting device equipped with
The phase modulation layer is
Basic layer and
A plurality of different refractive index regions having different refractive indexes from the basic layer,
With
When an XYZ Cartesian coordinate system with the thickness direction of the phase modulation layer as the Z-axis direction is set and a virtual square lattice with a lattice constant a is set in the XY plane,
Each of the different refractive index regions is
The position of the center of gravity is arranged so as to deviate from the position of the grid point in the virtual square grid by a distance r.
All the different refractive index regions have the same distance r in the XY plane.
The distance r is 0 <r ≦ 0.3a.
The beam pattern (excluding spots) emitted from the semiconductor light emitting device is
At least one:
Straight line,
cross,
Shape,
Photo,
CG (Computer Graphics) or
letter,
Including
The complex amplitude F (X, Y) obtained by two-dimensional Fourier transforming a specific region of the beam pattern in the XY plane has the intensity distribution I (X, Y) in the XY plane and the intensity distribution in the XY plane with j as an imaginary unit. Using the phase distribution P (X, Y) of:
Given by F (X, Y) = I (X, Y) x exp {P (X, Y) j},
In the phase modulation layer
Let φ be the angle formed by the X-axis and the direction from each lattice point of the virtual square lattice toward the center of gravity of each corresponding different refractive index region.
Let C be the constant
Assuming that the position of the x-th virtual grid point in the X-axis direction and the y-th virtual grid point in the Y-axis direction is (x, y) and the angle at the position (x, y) is φ (x, y),
φ (x, y) = C × P (X, Y) meets the,
The shape of each of the different refractive index regions in the XY plane is a square, a regular hexagon, a regular octagon, or a regular hexadecagon.
A semiconductor light emitting device characterized by this. With the active layer
A pair of clad layers sandwiching the active layer and
A phase modulation layer optically coupled to the active layer and
In a semiconductor light emitting device equipped with
The phase modulation layer is
Basic layer and
A plurality of different refractive index regions having different refractive indexes from the basic layer,
With
When an XYZ Cartesian coordinate system with the thickness direction of the phase modulation layer as the Z-axis direction is set and a virtual square lattice with a lattice constant a is set in the XY plane,
Each of the different refractive index regions is
The position of the center of gravity is arranged so as to deviate from the position of the lattice point in the virtual square lattice by a distance r.
All the different refractive index regions have the same distance r in the XY plane.
The distance r is 0 <r ≦ 0.3a.
The beam pattern (excluding spots) emitted from the semiconductor light emitting device is
At least one:
Straight line,
cross,
Shape,
Photo,
CG (Computer Graphics) or
letter,
Including
The complex amplitude F (X, Y) obtained by two-dimensional Fourier transforming a specific region of the beam pattern in the XY plane has the intensity distribution I (X, Y) in the XY plane and the intensity distribution in the XY plane with j as an imaginary unit. Using the phase distribution P (X, Y) of:
Given by F (X, Y) = I (X, Y) x exp {P (X, Y) j},
In the phase modulation layer
Let φ be the angle formed by the X-axis and the direction from each lattice point of the virtual square lattice toward the center of gravity of each corresponding different refractive index region.
Let C be the constant
Assuming that the position of the x-th virtual grid point in the X-axis direction and the y-th virtual grid point in the Y-axis direction is (x, y) and the angle at the position (x, y) is φ (x, y),
φ (x, y) = C × P (X, Y) meets the,
The shape of each of the different refractive index regions in the XY plane is
Rectangle,
Ellipse or
A shape in which parts of two circles or ellipses overlap,
A semiconductor light emitting device characterized by being. With the active layer
A pair of clad layers sandwiching the active layer and
A phase modulation layer optically coupled to the active layer and
In a semiconductor light emitting device equipped with
The phase modulation layer is
Basic layer and
A plurality of different refractive index regions having different refractive indexes from the basic layer,
With
When an XYZ Cartesian coordinate system with the thickness direction of the phase modulation layer as the Z-axis direction is set and a virtual square lattice with a lattice constant a is set in the XY plane,
Each of the different refractive index regions is
The position of the center of gravity is arranged so as to deviate from the position of the lattice point in the virtual square lattice by a distance r.
All the different refractive index regions have the same distance r in the XY plane.
The distance r is 0 <r ≦ 0.3a.
The beam pattern (excluding spots) emitted from the semiconductor light emitting device is
At least one:
Straight line,
cross,
Shape,
Photo,
CG (Computer Graphics) or
letter,
Including
The complex amplitude F (X, Y) obtained by two-dimensional Fourier transforming a specific region of the beam pattern in the XY plane has the intensity distribution I (X, Y) in the XY plane and the intensity distribution in the XY plane with j as an imaginary unit. Using the phase distribution P (X, Y) of:
Given by F (X, Y) = I (X, Y) x exp {P (X, Y) j},
In the phase modulation layer
Let φ be the angle formed by the X-axis and the direction from each lattice point of the virtual square lattice toward the center of gravity of each corresponding different refractive index region.
Let C be the constant
Assuming that the position of the x-th virtual grid point in the X-axis direction and the y-th virtual grid point in the Y-axis direction is (x, y) and the angle at the position (x, y) is φ (x, y),
φ (x, y) = C × P (X, Y) meets the,
The shape of each of the different refractive index regions in the XY plane is
Trapezoid,
A shape deformed so that the dimension in the minor axis direction near one end along the long axis of the ellipse is smaller than the dimension in the minor axis direction near the other end, or
A shape in which one end along the long axis of an ellipse is transformed into a sharp end that protrudes along the long axis.
A semiconductor light emitting device characterized by being. With the active layer
A pair of clad layers sandwiching the active layer and
A phase modulation layer optically coupled to the active layer and
In a semiconductor light emitting device equipped with
The phase modulation layer is
Basic layer and
A plurality of different refractive index regions having different refractive indexes from the basic layer,
With
When an XYZ Cartesian coordinate system with the thickness direction of the phase modulation layer as the Z-axis direction is set and a virtual square lattice with a lattice constant a is set in the XY plane,
Each of the different refractive index regions is
The position of the center of gravity is arranged so as to deviate from the position of the lattice point in the virtual square lattice by a distance r.
All the different refractive index regions have the same distance r in the XY plane.
The distance r is 0 <r ≦ 0.3a.
The beam pattern (excluding spots) emitted from the semiconductor light emitting device is
At least one:
Straight line,
cross,
Shape,
Photo,
CG (Computer Graphics) or
letter,
Including
The complex amplitude F (X, Y) obtained by two-dimensional Fourier transforming a specific region of the beam pattern in the XY plane has the intensity distribution I (X, Y) in the XY plane and the intensity distribution in the XY plane with j as an imaginary unit. Using the phase distribution P (X, Y) of:
Given by F (X, Y) = I (X, Y) x exp {P (X, Y) j},
In the phase modulation layer
Let φ be the angle formed by the X-axis and the direction from each lattice point of the virtual square lattice toward the center of gravity of each corresponding different refractive index region.
Let C be the constant
Assuming that the position of the x-th virtual grid point in the X-axis direction and the y-th virtual grid point in the Y-axis direction is (x, y) and the angle at the position (x, y) is φ (x, y),
φ (x, y) = C × P (X, Y) meets the,
When the effective refractive index of the phase modulation layer is n,
The wavelength λ ₀ (= 2 ^0.5 × a × n) selected by the phase modulation layer is
It is included in the emission wavelength range of the active layer.
A semiconductor light emitting device characterized by this. When the effective refractive index of the phase modulation layer is n,
The wavelength λ ₀ (= a × n) selected by the phase modulation layer is
It is included in the emission wavelength range of the active layer.
The semiconductor light emitting device according to any one of claims 1 to 3 . In the phase modulation layer, all the different refractive index regions are in the XY plane.
Same shape and / or
Have the same area and
The plurality of different refractive index regions can be superposed by a translation operation or a translation operation and a rotation operation.
The semiconductor light emitting device according to any one of claims 1 to 5 , wherein the semiconductor light emitting device is characterized. The shape of each of the different refractive index regions in the XY plane has rotational symmetry.
The semiconductor light emitting device according to any one of claims 1, 2, 4, 5 and 6 , characterized in that. The shape of each of the different refractive index regions in the XY plane has mirror image symmetry.
The semiconductor light emitting device according to any one of claims 1, 2, 4, 5, 6 and 7, characterized in that. The phase modulation layer is
An inner region in which a substantially periodic structure of the different refractive index region for emitting a target beam pattern is formed, and
An outer region that surrounds the inner region and includes the different refractive index region whose center of gravity is aligned with the grid point position of the square lattice.
The semiconductor light emitting device according to any one of claims 1 to 8 , wherein the semiconductor light emitting device is provided.